package cuppics;

import java.util.ArrayList;
import java.util.List;

import org.junit.Test;

public class Prj8 {

	/**
	 * The four adjacent digits in the 1000-digit number that have the greatest
	 * product are 9 × 9 × 8 × 9 = 5832.
	 * 
	 * 73167176531330624919225119674426574742355349194934
	 * 96983520312774506326239578318016984801869478851843
	 * 85861560789112949495459501737958331952853208805511
	 * 12540698747158523863050715693290963295227443043557
	 * 66896648950445244523161731856403098711121722383113
	 * 62229893423380308135336276614282806444486645238749
	 * 30358907296290491560440772390713810515859307960866
	 * 70172427121883998797908792274921901699720888093776
	 * 65727333001053367881220235421809751254540594752243
	 * 52584907711670556013604839586446706324415722155397
	 * 53697817977846174064955149290862569321978468622482
	 * 83972241375657056057490261407972968652414535100474
	 * 82166370484403199890008895243450658541227588666881
	 * 16427171479924442928230863465674813919123162824586
	 * 17866458359124566529476545682848912883142607690042
	 * 24219022671055626321111109370544217506941658960408
	 * 07198403850962455444362981230987879927244284909188
	 * 84580156166097919133875499200524063689912560717606
	 * 05886116467109405077541002256983155200055935729725
	 * 71636269561882670428252483600823257530420752963450 Find the thirteen
	 * adjacent digits in the 1000-digit number that have the greatest product.
	 * What is the value of this product?
	 */
	@Test
	public void test() {

		Region rg = new Region(0, 0).getLargest(VAL_STR);

		System.out.println(" start = " + rg.start + ",end =" + rg.end
				+ " ,val =" + rg.maxValue);
	}

	public static final String VAL_STR = "73167176531330624919225119674426574742355349194934"
			+ "96983520312774506326239578318016984801869478851843"
			+ "85861560789112949495459501737958331952853208805511"
			+ "12540698747158523863050715693290963295227443043557"
			+ "66896648950445244523161731856403098711121722383113"
			+ "62229893423380308135336276614282806444486645238749"
			+ "30358907296290491560440772390713810515859307960866"
			+ "70172427121883998797908792274921901699720888093776"
			+ "65727333001053367881220235421809751254540594752243"
			+ "52584907711670556013604839586446706324415722155397"
			+ "53697817977846174064955149290862569321978468622482"
			+ "83972241375657056057490261407972968652414535100474"
			+ "82166370484403199890008895243450658541227588666881"
			+ "16427171479924442928230863465674813919123162824586"
			+ "17866458359124566529476545682848912883142607690042"
			+ "24219022671055626321111109370544217506941658960408"
			+ "07198403850962455444362981230987879927244284909188"
			+ "84580156166097919133875499200524063689912560717606"
			+ "05886116467109405077541002256983155200055935729725"
			+ "71636269561882670428252483600823257530420752963450";

	public static class Region {

		public Region(int start, int end) {
			this.start = start;
			this.end = end;
		}

		public int start;
		public int end;

		public Long maxValue = (long) 0;

		private char[] getCharArr(String valStr) {
			char[] charArr = new char[valStr.length()];

			valStr.getChars(0, valStr.length(), charArr, 0);
			return charArr;
		}

		List<Region> parserRegion(char[] charArr) {
			List<Region> ret = new ArrayList<Region>();
			List<Integer> zeroId = new ArrayList<Integer>();
			for (int i = 0; i < charArr.length; i++) {

				if (charArr[i] == '0') {
					zeroId.add(i);
				}
			}

			for (int i = 0; i < zeroId.size() - 1; i++) {

				int start = zeroId.get(i);
				int end = zeroId.get(i + 1);
				if (i == 0) {
					if (start != 0) {
						if (start + 1 > 13) {
							Region rg = new Region(0, start);
							ret.add(rg);
						}
					} else {

						if (end - start + 1 > 13) {
							Region rg = new Region(start, end);
							ret.add(rg);
						}
					}

					continue;
				}

				if (end - start + 1 > 13) {
					Region rg = new Region(start, end);
					ret.add(rg);
				}

			}

			return ret;

		}

		Region calculateMax(Region rg, char[] charArr) {

			Region ret = new Region(rg.start, rg.end);
			Long sum = 1L;
			for (int i = rg.start; i <= rg.end - 13 + 1; i++) {

				Long tmp = 1L;
				for (int j = 0; j < 13; j++) {
					tmp = tmp
							* Integer.parseInt(new String(
									new char[] { charArr[i + j] }));

				}
				if (tmp > sum) {
					sum = tmp;
					ret.start = i;
					ret.end = i + 13;
					ret.maxValue = sum;
				}
			}
			return ret;
		}

		public Region getLargest(String valStr) {

			Region ret = null;

			char[] charArr = getCharArr(valStr);
			List<Region> regions = parserRegion(charArr);

			Long sum = 1L;
			for (Region rg : regions) {

				Region calculateRg = calculateMax(rg, charArr);
				if (calculateRg.maxValue > sum) {
					sum = calculateRg.maxValue;
					ret = calculateRg;
				}
			}

			return ret;
		}
	}
}
